LONDON (Reuters) -Apple ( AAPL ) on Friday lost a bid to throw out a mass lawsuit valued at just under $1 billion, brought in London on behalf of more than 1,500 app developers over its App Store fees.

The case, worth up to 785 million pounds ($979 million) and one of several faced by the U.S. tech giant in the United Kingdom, alleges Apple ( AAPL ) charged third-party developers unfair commissions of up to 30% on purchases of apps or other content.

Sean Ennis, a competition law professor and economist, is spearheading the case which was filed at the Competition Appeal Tribunal (CAT) last year.

His lawyers say Apple ( AAPL ) has abused its dominant position in the market for the distribution of apps on iPhones and other Apple ( AAPL ) devices and are seeking damages for UK-based developers.

Apple ( AAPL ), however, says 85% of developers on its App Store do not pay any commission at all.

Its lawyer Daniel Piccinin argued at a hearing in January that developers cannot have a claim in the UK unless they were charged on purchases made through the UK App Store.

But the company's bid to throw out that part of the case was rejected on Friday.

Judge Andrew Lenon said in a written ruling that Ennis' lawyers had a realistic prospect of establishing that "Apple's ( AAPL ) overcharging of commission to app developers based in the UK in relation to commerce transacted on non-UK storefronts did amount to conduct implemented in the UK".